A gas turbine engine compressor typically includes inlet guide vanes followed by a row, or stage of compressor rotor blades. During operation, air flows through the inlet guide vane and is sequentially compressed by the compressor stages.
Inlet guide vanes are used to meter the amount of airflow through the compressor. Variable inlet guide vane assemblies use blades that can be individually rotated around their axis, as opposed to the power axis of the engine. The vanes are arranged in an annular duct and are rotated in synchronization to change the open area of the duct, allowing more or less air to pass therethrough.
Vane movement is accomplished by coupling a sector gear on each of the vanes to a common actuation ring gear for providing uniform adjustment of the individual vanes in order to dynamically change their position. Each vane must be identically angled relative to the other vanes in the ring to maximize efficiency and prevent undesirable aerodynamic distortion from a misaligned vane. After some period of use, and under some engine operating conditions, the meshed gears may bind, inhibiting the ability to change the position of the inlet guide vane.
Improvements in variable inlet guide vanes are therefore needed in the art.